LDLARB

Load LOAcquire register byte

This instruction loads a byte from memory, zero-extends it and writes it to a register.

If the destination register is not one of WZR or XZR, LDLARB loads from memory with Acquire semantics.

For more information about memory ordering semantics, see Load LOAcquire, Store LORelease and Load-Acquire, Load-AcquirePC, and Store-Release.

For information about addressing modes, see Load/Store addressing modes.

No offset class

(FEAT_LOR)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
0	0	0	0	1	0	0	0	1	1	0	(1)	(1)	(1)	(1)	(1)	0	(1)	(1)	(1)	(1)	(1)	Rn					Rt
size									L		Rs					o0	Rt2

Encoding

LDLARB <Wt>, [<Xn|SP>{, #0}]

Decode

if !IsFeatureImplemented(FEAT_LOR) then EndOfDecode(Decode_UNDEF); constant integer t = UInt(Rt); constant integer n = UInt(Rn); constant boolean acquire = t != 31; constant boolean tagchecked = n != 31;

Assembler Symbols

<Wt>	Is the 32-bit name of the general-purpose register to be transferred, encoded in the "Rt" field.

<Xn|SP>

Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.

Operation

bits(64) address; constant AccessDescriptor accdesc = CreateAccDescLOR(MemOp_LOAD, tagchecked, acquire, t); if n == 31 then CheckSPAlignment(); address = SP[64]; else address = X[n, 64]; constant bits(8) data = Mem[address, 1, accdesc]; X[t, 32] = ZeroExtend(data, 32);

Operational information

This instruction is a data-independent-time instruction as described in About PSTATE.DIT.

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